Vibratory feeding work station module and system

ABSTRACT

A work station module which includes a buffer storage area (B) for the transitory storage of workpiece carriers (A) which are received at non-specific intervals and an escapement station (C) to facilitate performance of some operation of a workpiece carried by each carrier. The buffer storage area includes a conveying surface (30) which is defined by a multiplicity of fibers (36) and which is vibrated to move the carriers longitudinally therealong. The resiliency of the fibers permits carriers which are adjacent the escapement station to remain stationary even though the conveying surface is vibrating. A directing rail (50) extends upward through the fibers and terminates just below their upper surface such that the carriers are supported on the fibers and not the directing rail. The carrier includes a plurality of pins (18, 20) which extend downward therefrom to define a slot for receiving the rail. At the escapement station, the carriers are decelerated by engagement with a friction drag surface (62) and are brought into general alignment with the escapement station by a stop surface (60). The carriers are lifted by arms (72) and brought into more accurate alignment with the escapement station by the interaction of pins (70) on the arms and bushings (24) in the carriers. A precision alignment pin (90) and an associated bushing (26) bring the carrier and escapement station into accurate alignment to facilitate performance of an automatic operation on the workpiece carried thereon.

BACKGROUND OF THE INVENTION

This application is a continuation-in-part of application Ser. No.310,083, filed Oct. 9, 1981, now U.S. Pat. No. 4,444,303.

This application pertains to the art of workpiece handling andparticularly to vibratory feeders for handling and conveying workpiecesbetween successive work or escapement stations.

The invention is particularly applicable to interconnectable modularwork stations which may be connected end to end in an array such thatthe workpieces are moved from module to module. Each module is adaptedto facilitate a specific manufacturing operation or function such asassembly, polishing, drilling, and the like. Fundamental to thisinvention, each module may operate on a permissive basis, i.e., as soonas a carrier is in place, the operation of that particular module isexecuted. Each module therefore operates independently from all othermodules. This system is often referred to as a non-synchronous system.In a synchronous system stations must operate simultaneously. It will beappreciated, however, that those skilled in the art may readily adaptthe invention to other manufacturing operations as well as toalternative handling and processing arrangements or environments.

Heretofore, various non-synchronous manufacturing assemblies have beendevised in which workpieces are placed on a pallet or other carrier andmoved automatically from one work station to another. In one suchassembly, a series of pallets were adapted for selective engagement withand disengagement from a continuously moving chain. When a palletreached a work station, it automatically disengaged the chain inanticipation of the operation being performed. Once the operation hadbeen completed, the pallet reengaged the chain and was moved to the nextwork station. In that system, the pallets tended to be suddenlyaccelerated and deaccelerated resulting in frequent impacts with eachother. Moreover, the equipment utilized was slower than synchronoussystems, complicated, expensive, and best suited for use with largeworkpieces such as engine blocks, transmission assemblies, and the like.

Others in the field have made non-synchronous systems in whichindependent belt drives moved pallets containing workpieces between workstations. The belt drives could be interrupted between work stations toallow the pallet and attached workpieces to be tipped, rotated, moved at90° or other angles, or otherwise have their orientation adjusted tofacilitate the next operation. To protect employees from the beltdrives, extensive guards were required therealong. On a given belt, thepallets were maintained at fixed intervals which could not be contractedor eliminated. Further, the belts were constrained to move all palletsalong the belt simultaneously and, thus, could not receive a pallet atone end without sliding the belt along the underside of the carriersheld stationary thereon, causing excessive belt wear and maintenance.Such systems, again, were complicated, expensive and not well suited tothe assembly of moderate or small components. Further, the speed of suchsystems was not easily changed or adjusted to accommodate productivityimprovements that accompany putting a machine into production.

Vibratory feeders have been used for many years to convey workpiecesfrom one location to another. The jostling movement caused by vibratoryfeeders is unsuitable for some subassemblies, workpieces, or partiallyassembled workpieces. For example, if a shallow race containing aplurality of ball bearings were to be transported, the ball bearingswould tend to bounce out of the race. A similar problem would tend toarise in the other prior art systems in which the pallets wereaccelerated or deaccelerated suddenly. It is further known in vibratoryfeeders to line the feeder with polypropylene fiber material to reducenoise and protect delicate parts.

SUMMARY OF THE INVENTION

The present invention contemplates a new and improved non-synchronousconveying system which overcomes the above-referenced problems andothers. A plurality of workpiece carriers are directed along a fiberconveying surface by a guide rail system. A motivating meanscontinuously urges the carriers along the conveying surface. Stop meansselectively stop the carriers to facilitate performance of manual,semi-automatic, or automatic operations on the carried workpieces.

In accordance with a more limited aspect of the present invention, adecelerating means is provided in conjunction with the stop means fordecelerating the carriers to a smooth stop.

In accordance with another more limited aspect of the present invention,an escapement station is provided in association with at least some ofthe stop means. As the escapement station lifts each carrier which hasbeen preliminarily aligned by the stop means, the carrier is broughtinto more accurate alignment. With continued lifting, a third aligningmeans brings the carrier into precise alignment with the escapementstation.

In accordance with yet another aspect of the invention, a plurality ofescapement stations are provided along the conveying surface. Bufferstorage areas are provided upstream from at least some of the escapementstations. When a system is first set up, manual operations may beperformed at many of the escapement stations. As the production rateincreases, the manual operation escapement stations may be replaced bysemi-automatic and automatic stations.

A principal advantage of the present invention is that workpieces arestarted, stopped, and conveyed smoothly, quietly, and quickly betweenescapement or work stations without disrupting partially assembled ormanufactured workpieces. The workpieces may be conveyed at two to fourtimes the speed of normal vibratory feeders. Such a non-synchronoussystem runs at speeds comparable to synchronous systems.

Another primary advantage of the present invention is that workpiececarriers or boats are started, conveyed, and stopped on a conveyingsurface virtually without wear on the carriers or conveying surface.

Another advantage of the invention resides in the provision of a workstation module which may be readily interconnected with similar ordifferent modules to facilitate performing a preselected sequence ofmanufacturing operations.

A further advantage of the invention is in the provision of a free flowor free wheeling, non-synchronous type system where each of theinterconnected station modules handles the workpieces independently ofthe other modules.

Another advantage is the precision positioning of workpieces relative toan automated tool or the like, up to five times the precision ofsynchronous systems.

Yet another advantage of the invention is that it provides means whichare readily adapted or converted to performing a variety of workpieceoperations such as assembling, drilling, polishing, inspecting, and thelike.

Still further advantages will become readily apparent to those skilledin the art upon reading and understanding the following detaileddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may take physical form in various parts and arrangementsof parts. The drawings are only for purposes of illustrating a preferredphysical arrangement or embodiment and are not to be construed aslimiting the invention.

FIG. 1 is a perspective view of a work station module constructed inaccordance with the present invention;

FIG. 2 is an end elevational view of an escapement station of the moduleof FIG. 1 in partial section;

FIG. 3 is a top plan view in partial section of a deceleration andpositioning mechanism for decelerating and positioning workpiececarriers relative to the work station modules;

FIG. 4 is a side elevational view of the deceleration and positioningmodule of FIG. 3; and,

FIG. 5 is a diagrammatic top plan view of a plurality of work stationsmodules interconnected into a linear free flow manufacturing andassembly system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 illustrates a work station module for handling a plurality ofworkpiece carriers or boats A. The module includes a buffer storage areaB for transitory storage of a plurality of the carriers which itreceives at non-specific intervals and an escapement station C whichfacilitates performance of a manufacturing operation on the workpiececarried by each carrier. The interval between operations of theescapement station is not necessarily coextensive with the intervalbetween receiving workpiece carriers. The escapement station operates ona "permissive" type cycle in which it commences an operation in responseto its completion of the preceding operation and the arrival of a newcarrier rather than in response to the cycling of another machine orescapement station. This allows each escapement station to cycle at thehighest speed possible for the operation which it performs.

With reference to FIGS. 1 and 2, the workpiece carriers A include a wideflat base 10 on which at least one nest 12 or other means for mounting aworkpiece is disposed. Optionally, a plurality of nests may be providedto allow the escapement station to operate simultaneously on a pluralityof workpieces per carrier. For simplicity of illustration, the nest 12is shown in the form of a hollow cylinder disposed on the upper surfaceof the carrier for holding the workpieces. Other nests or workpiecemounting means such as threaded bores in the base 10 to receive boltsthrough the workpieces, bores in the base to receive pins projectingfrom the workpieces, magnets imbedded in the base, spring clips mountedon the base, and the like are also contemplated as nests for mountingthe workpieces on the carrier with a preselected orientation andposition.

With particular reference to FIG. 2, the carrier has a planar, conveyorengaging surface 14 which, optionally, may be abraded or grooved. Thecarrier also includes a guide means 16 for guiding the position andorientation of the carrier relative to the buffer storage area B and theescapement station C. The carrier guide means includes means fordefining at least one guide or directing rail receiving slot on theengaging surface. In the preferred embodiment, the carrier guide meansdefines the guide rail receiving slot with at least one pair of guidepins 18, 20 and preferrably with two pairs. Optionally, the guide slotmay be defined by a pair of continuous or discontinuous strips, by achannel cut into the engaging surface 14, or the like.

The carrier further includes alignment means for aligning the carrierwith the escapement station. The alignment means includes first, second,and third aligning means for progressively aligning the carrier moreaccurately with the escapement station. The first aligning meansincludes a flag 22 which may also carry encoded information. The secondaligning means includes a plurality of lower alignment apertures orbushings 24 in the engaging surface 14. The third aligning meansincludes a plurality of precision hardened pin receiving bushings 26disposed on the upper surface of the carrier base 10. Each carrier alsoincludes resilient bumpers 28 for reducing jarring when carriers meet.

Continuing with reference to FIGS. 1 and 2, the buffer storage area Bincludes a conveying surface 30 along which workpieces are moved from afirst or upstream end 32 toward a second or downstream end 34. Theconveying surface 30 is defined by a multiplicity of fibers 36 whichproject from a layer of resilient plastic layer 38. One end of eachfiber is imbedded in the plastic layer 38 and the free end is adapted toengage the engaging surface 14 of the carriers A. As is already known,the fibers slope a few degrees from vertical with the free ends thereofbeing angled toward the downstream end 34 of the module. In thepreferred embodiment, the fibers are polypropylene, although otherresilient, wear-resistant fibers may be used to advantage.

A motivating means, includes a motor 40 which selectively causes theconveying surface to undergo a mode motion which includes vertical andlongitudinal components of motion. In the preferred embodiment, a majorforward component of the motion is along a line about 15 to 20 degreesabove horizontal. The fibers lean forward at about 50° to 75° relativeto the line of movement. A plurality of leaf springs 42 connect themotor, the conveying surface 30, and counter weight 44. The motivatingmeans urges the fibers against the carriers A causing the fibers tobuckle slightly and raise the carriers as they attempt to resume theirstraight characteristic. This vibration of the inclined, resilientfibers results in a fast, quiet, and abrasion-free conveying action.

With particular reference to FIG. 2, the guide means 16 further includesdirecting means for interacting with the carrier slot for directing thecarriers along the conveying surface 30. In the preferred embodiment,this directing means includes a central guide or directing rail 50 whichis received between guide pins 18, 20 of the carrier. Optionally,additional guide or directing rails may be received in the additionalguide slots of the carriers. The guide or directing rail, in thepreferred embodiment, has a frictional reducing surface of TEFLON,NYLON, fibers, or the like, for inhibiting lateral movement of thecarriers with a minimum of drag. More particularly, the rail isconstructed of the friction reducing material and has a generallyrectangular cross section. Adjacent the escapement station C, the rail50 has a tapered upper surface to facilitate return of the carrier afterthe performance of a work operation.

In the preferred embodiment shown, the directing rail 50 is connectedwith the conveying surface 30 to undergo vibratory motion therewith.Because each carrier is supported directly by the fibers 36 and not bythe directing rail 50, the guide means may take other forms, such as apair of side rails received in a corresponding grooves in the carrier orthe like. Alternately, bearings or rollers may be provided between theguide pins or rollers 18 and 20 or the engaging surface, and thedirecting rail 50. It is to be appreciated that the fibers 36 are ableto carry relatively heavy loads, on the order of five pounds or so persquare inch of carrier base 10. The load carrying capability does,however, vary with the fiber density, and the composition density, anddenier of the fibers.

Still referring to FIGS. 1 and 2, the escapement station C of thepreferred embodiment is disposed downstream from the buffer storage areaB of the same module toward the second end 34 of the conveying surface30. Optionally, the buffer storage area may be adjacent the downstreamend to serve an escapement station at the upstream end of the nextmodule. It will be appreciated that the escapement station may takevarious forms which are particularly adapted to perform selectedworkpiece operations.

The alignment means includes escapement station mounted portions forinteracting with the carrier mounted portions of the first, second, andthird aligning means for progressively aligning and precisely fixing theposition of the carrier relative to the escapement station. Withparticular reference to FIGS. 1, 3, and 4, the escapement stationportion of the first aligning means includes a first retractable, stopsurface 60 which selectively engages the forwardmost face of the flag22. The first stop surface is selectively retractable to allow thealigned boat to advance after the appropriate operation has beenperformed at the escapement station.

More specifically, the first aligning means operates in conjunction witha decelerating means 62 for smoothly decelerating and stopping eachreceived carrier. The decelerating means includes a friction surface 64which frictionally engages a leading outside corner or edge of the flag22 causing a drag thereon. The first stop surface 60 and the frictionsurface 62 are portions of a pivotally mounted deceleration and stoppingmember 66. A control cylinder 68 selectively controls pivoting of thedeceleration and stopping member 66. Specifically, the air cylinderbiases the deceleration and stopping member toward the carrier path suchthat it engages the outward surface of the flag and is pivoted towardthe cylinder by the interaction therewith. The degree and rapidity withwhich the deceleration and stop member 66 yields is determined by thebiasing force applied by the cylinder 68. In the preferred embodiment,the cylinder 68 is an air cylinder into which compressed air isdirected. By selectively adjusting the pressure in the air cylinder, thedeceleration rate of the carriers is selectively adjusted. After theoperation has been performed by the escapement station and the carrieris to pass downstream, the cylinder 68 is selectively actuated towithdraw the first stop surface 60 from interaction with the flag.

The deceleration means further includes a buffer storage areadeceleration means 62' of substantially the same construction as theescapement station deceleration means 62. For simplicity ofillustration, corresponding elements of the buffer deceleration meansand the escapement station deceleration means are described with thesame reference numerals but followed by a prime ('). A friction surface64' of a deceleration and stop member 66' is biased into the path of acarrier flag by an air or other buffer area control cylinder 68'. As oneor a plurality of carriers in the buffer storage area advance, thefrictional interaction between the flag and the friction surface 64'decelerates the carriers. The selective yielding of the buffer areacontrol cylinder 68' determines the rate of deceleration. In thepreferred embodiment, the buffer area deceleration control cylinder 68'supplies a greater biasing force than escapement station decelerationcontrol cylinder 68 because the buffer decelerating means 62' commonlydecelerates a plurality of carriers, i.e., many times greater mass thanthe escapement station decelerating means 62 which only decelerates asingle carrier. The buffer area deceleration control cylinder 68' isselectively retractable such that a stop surface 60' disengages theforwardmost face of the carrier flag allowing the leading carrier in thebuffer storage area to advance to the escapement station.

Referring again to FIGS. 1 and 2, the escapement station mounted portionof the second aligning means is disposed in association with a conveyingsurface disengaging means for selectively lifting or disengaging thecarrier from the conveying surface 30. This prevents an operationperformed at the escapement station from interfering with the vibratorymotion of the conveying surface. Conversely, this prevents the vibratorymotion of the conveying surface from interfering with the performedoperation. The second aligning means includes a plurality of taperedalignment pins 70 which are mounted on associated lifting arms 72. Thealignment pins are selectively received in the lower bushings 24 asshoulders on the lifting arms raise the carrier. In this manner, as thelifting arms 72 move upward to lift the carrier from the conveyingsurface, the tapered pins 70 and the lower bushings 24 align the carrierwith the escapement station. The lifting arms extend through enlargedopenings in the conveying surface 30 and openings in the fibers 36 suchthat the lifting arms move through the conveying surface withoutinterfering with its vibratory movement.

Further to the preferred embodiment, the lifting arms 72 are mounted ona platen 74 which is mounted on a shaft 76 that is non-rotatably mountedin a square bearing 78. A universal, T-drive-type coupling 80 joins thecylindrical shaft 76 with a lifting control cylinder 82, preferrably apneumatic cylinder. To lift a received carrier, the cylinder 82 isselectively actuated causing the T-drive 80, the shaft 76, and theplaten 74 to lift the lifting arms 72. A moderate clearance between thealigning pins 70 and the lower alignment apertures or bushings 24 allowsthe alignment pins to move smoothly into the lower alignment aperturesor bushings. This smooth interaction permits the carrier to be liftedsmoothly by the lifting arms without jostling the parts carried thereby.

Resilient dampers 84 are brought into intimate contact with the balanceweights 44. This prevents lateral shifting of the balance weights which,in turn, prevents lateral shifting of the guide rail 50 during the workoperation and assures dependable operation over a long period of time.

The escapement station mounted portion of the third aligning meansincludes a pair of hardened pins 90 which are received in the upperbushings 26 with a close tolerance. The progressively closer tolerancesprovided by the first, second, and third aligning means enable the thirdaligning means to provide very precise alignment between the workpieceand the escapement station. Further, the progressive alignment enablesthe aligning means, particularly the third aligning means, to havesmooth interaction between the pins and bushings, hence, little wear andlittle jostling of carrier parts. The disengaging means moves thecarrier and the upper bushings to the hardened pins 90. If desired, thealignment pins 90 may be connected with a switch for indicating that thecarrier is properly aligned and starting the escapement stationoperation.

The escapement station further includes an escapement mounting means 92for mounting an apparatus or tool 94 which performs the preselectedescapement station operation. The mounting means 92 may take any numberof different forms and is adapted to cooperate with the specificapparatus or tool 94 selected and/or required. Optionally, theescapement station may include a decoder for decoding informationencoded on flag 22 to cause a corresponding operation to be performed bythe escapement station, or an encoder for encoding the flag withinformation about the escapement station operation.

As shown in FIG. 1, the buffer storage area B and escapement station Care mounted on a frame structure which includes a horizontal supportingportion 100 and a pair of supports 102 and 104. These supports includehorizontal supporting members 106 and 108 extending therebetween forsupporting the horizontal supporting portions of a pair of adjacentmodules. Leveling means 110 are advantageously provided to facilitateadjustment of conveying surface 30 to a substantially horizontalposition. Various interconnecting means such as bolt holes 112 and thelike allow each module to be accurately aligned and interconnected withan adjacent module.

In the free flow system, each carrier or boat A is received at theupstream end 32 of the conveying surface 30 of one or a first of themodules and is moved therealong by the vibratory motion of the fibers36. Upon abutting another carrier in the buffer storage area B, thecarrier stops moving and the fibers buckle and extend without moving thecarrier forward. When the escapement station has completed amanufacturing operation, the escapement station stop surface 60 iswithdrawn and the lift arms 72 lower the carrier from the escapementstation C onto the vibrating conveyor surface. The carrier is thenconveyed downstream along the conveying surface of the next adjacentmodule toward the buffer storage area thereof. The lead carrier in thebuffer storage area is released by the buffer area stop surface 60',conveyed into the escapement station, and brought to a stop by theescapement station deceleration means 62 and stop 60, thus providingfirst or preliminary alignment without jarring or vibrating thetransported workpiece. The line of carriers in the buffer storage areamove forward and are decelerated by the buffer area deceleration means62' and stop against the buffer area stop surface 60'. The lift arms 72align and lift the carrier in the escapement station for performance ofthe work operation. The foregoing operational steps are then repeated.

It will be appreciated that the carriers are moved independently of theoperation of other escapement stations. If an escapement station takesabnormally long to perform its operation, more carriers are accumulatedin the buffer storage area of that module. Conversely, if themanufacturing operation is performed quickly, the number of carriers inthe buffer storage area is reduced. In this manner, fluctuations in thetime required for performing manufacturing operations or extricating badparts at any modules in the line do not affect operation of the othermodules. For example, in a ten operation non-synchronous assemblysystem, if each of the ten escapement stations operates with 95%productivity due to misformed parts and other malfunctions, theproductivity of the non-synchronous assembly system is substantially95%. By contrast in a ten operation synchronous system in which each ofthe operations has a 95% productivity, the productivities are compoundedand the overall productivity of the system is 0.95₁₀ or 59.9%. In anassembly system with a machine rate of 60 parts per minute, over 2.5million additional parts per year are produced by the non-synchronousassembly system.

Referring now to FIG. 5, a free flow system is illustrated which is madeup of a plurality of the modules. Each of the modules may be likeFIG. 1. Optionally, some of the modules may have only a buffer storagearea with no escapement stations; other modules may have a plurality ofescapement stations. The plurality of escapement stations need not havebuffer storage areas therebetween. The work station modules areinterconnected in a closed loop so that each carrier may circulatesequentially from escapement station to escapement station independentlyof the movement of the other carriers. A work station module 200 has anupstream end 202 at which it receives workpiece carriers from apreceding module 204 and a downstream end 206 at which it dischargescarriers to a subsequent module 208. The module 200 includes anescapement station 210 at which an operation is performed. In theexample of FIG. 5, the escapement station 210 includes a vibratory bowlfeeder 212 for orienting and feeding components to be added to theworkpiece held on each carrier. An exemplary operation may be placing abearing race into the nest 12 of the carrier. As a further example, thesubsequent work station module 208 might grease the race, a later workstation module 214 may add a plurality of bearings to the race, and soon. The work station modules may be automatic as illustrated by modules200, 208, and 214, or may be manual as illustrated at module 216. In amanual operation module, each carrier is held in the escapement stationas an operator performs a manual assembly operation, inspection, or thelike. It is contemplated that the system may be built initially with allmanual assembly operations. As the production rate increases, theslowest manual assembly operations are replaced with automatic assemblytools. Further, if one of the automated modules malfunctions, theautomatic tool may be disconnected so that an operator may perform thesame manufacturing operation manually.

It will be appreciated that the modules may be connected in other than alinear line. For example, if several of the operations to be performedby the escapement means take longer than the others, a switching meansmay connect the second end of one of the modules with a pair of lines ofinterconnected modules such that alternate carriers are conveyed intoeach of the two parallel lines. The switching means may include apivotally mounted center directing rail and controller for selectivelymoving the rail to direct a carrier along a selected one of theplurality of lines. At the end of the parallel lines, all carriers maybe fed to the first end of a common module such as with a Y-likeconnection portion of the central rail. The modules may beinterconnected in various arrangements of linear paths, parallel paths,bypasses, and the like as required by the operation to be performed.

The invention has been described with reference to the preferred andalternative embodiments. Clearly, modifications and alterations willbecome apparent to others upon a reading and understanding the precedingdetailed description. It is intended that the invention be construed toinclude all such modifications and alterations insofar as they comewithin the scope of the appended claims or the equivalents thereof.

Having thus described a preferred embodiment, the invention is nowclaimed to be:
 1. A system for conveying the workpieces comprising:aplurality of workpiece carriers for carrying workpieces, each workpiececarrier having at least one nest means for receiving and holding aworkpiece; a conveying surface along which the workpiece carriers aremoved, the conveying surface including a multiplicity of resilientfibers projecting outward therefrom to engage the workpiece carriers;vibrating means for vibrating the conveying surface, such that thecarriers move therealong; at least one directing rail mounted on theconveying surface adjacent the resilient fibers and a rail receivingslot defining means on the carrier for receiving the conveying surfacedirecting rail therebetween, each carrier being supported by the fibersand being disposed in a non-supported association with the directingrail, the directing rail terminating in an upper surface disposed belowupper ends of the fibers such that the carrier is supported by thefibers rather than the directing rail and is disposed generallycentrally along the conveying surface with the fibers spaced a shortdistance therefrom and wherein the slot defining means includes aplurality of pins extending downward from the carrier fiber engaging ofpins extending downward from the carrier fiber engaging surface into thespace defined between the fibers and the guide rail; and, an alignmentmeans for aligning the carriers in a predetermined relationship with awork station whereby a preselected operation can be performedautomatically on the carrier workpiece.